1. Field of the Invention
The present invention relates in general to rack and pinion steering gears for road vehicles and more particularly to a ball joint for joining a rack gear to an inner end of a side rod or tie rod whose outer end is joined to a knuckle arm.
2. Description of the Prior Art
A road vehicle rack and pinion steering gear includes a pinion adapted to be rotated by a manually operated steering wheel and a rack gear meshed with the pinion for lateral reciprocating motion. The rack gear is joined to the inner ends of tie rods by means of ball joints. The outer ends of the tie rods are connected to knuckle arms which in turn are connected to steerable vehicle wheels so that rotation of the steering wheel causes the pinion to rotate and move the rack gear which in turn causes the tie rods and the knuckle arms to move and turn the steerable vehicle wheels
Arrangement of such ball joints is important since it is closely related to the toe change characteristic of the steering gear, as is well known in the art. An example of a ball joint arrangement which is effective for minimizing toe change is disclosed in the Japanese Provisional Patent Publication No. 58-97561. In this arrangement, such a ball joint is utilized whose center of rotary motion is offset from the center axis of the rack gear. However, the direction in which the center of rotary motion is set apart from the center axis of the rack gear is not changeable but fixed. Due to this, the toe change characteristic of the steering gear is not adjustable. Furthermore, in the above ball joint arrangement, the rack gear is required to have a pair of transverse taper holes adapted to receive therein correspondingly tapered shanks ending in balls and also to have a pair of flat cuts for providing seats on which nuts for attachment of the shanks are placed. Such transverse taper holes and the flat cuts inevitably result in an increased overall thickness and weight of the rack gear due to the necessity of increasing the strength of same.